Abstract:

Objective To evaluate the therapeutic effect of glycyrrhizic acid ointment on chronic eczema in guinea pigs. Methods Totally, 60 Kunming male mice, 60 Kunming mice and 60 albino guinea pigs were respectively classified into 6 groups: model group, ointment base group, dexamethasone group, high-, medium- and low-dose glycyrrhizic acid group. To observe the effect of glycyrrhizic acid ointment on the swelling of mouse auricles, dexamethasone and different doses of glycyrrhizic acid ointment were topically applied to both auricles of male mice in corresponding groups followed by the establishement of mouse auricle swelling model induced by xylene. One and a half hours later, the mice were sacrificed, and the weight of swelling auricles was weighed. Scratching behavior was induced by dextran 40 in Kunming mice following the application of dexamethasone or glycyrrhizic acid ointment. The latent period and frequency of scraching were recorded for every Kunming mice. To establish a model of eczema, guinea pigs were sensitized with dinitrochlorobenzene （DNCB, 5%） in the neck and back and challenged by DNCB （0.1%） on the inner surface of right ears once a week for 4 weeks; subsequently, both auricles were treated with dexamethasone or glycyrrhizic acid ointment once a day for 10 days. Then, the thickness of auricles of guinea pigs was measured, and skin tissue was obtained from the right ear of guinea pigs and subjected to a pathological analysis. Results The high- and medium-dose of glycyrrhizic acid ointment could suppress the xylene-induced swelling of mouse auricles （P < 0.05 or P < 0.01）. The latent period of scratching could be lengthened by high dose of glycyrrhizic acid（P < 0.05）. The three doses of glycyrrhizic acid all reduced scratching frequency in Kunming mice（P < 0.05 or P < 0.01）. Attenuated swelling of auricles （P < 0.05 or P < 0.01） and relieved pathological changes were observed in guinea pigs after treatment with glycyrrhizic acid ointment. Conclusion Glycyrrhizic acid ointment shows a therapeutic effect on chronic eczema in guinea pigs.

Key words: Pharmacodynamics